Participation in the study will begin at the socket duplication stage/initial testing phase and end no more than a week later after the second collection day is complete. Subjects will meet individually with the PI at lab on testing day one to have their socket duplicated and do some initial testing. Socket duplication will consist of filling the inside volume of the socket with a plaster mixture to form a positive mold. Once set, this positive mold can be removed and used by a contractor to form the clear thermoplastic socket over it. After the mold has been made, the subject will perform a series of tasks while being recorded by an 8 camera Vicon motion analysis system and 2 digital video cameras. Thirty reflective markers will be placed on the subject using an adhesive collar. There is slight risk of skin irritation due to the adhesive tape, similar to wearing a Band-Aid. Some discomfort may arise while removing the markers. A tight fitting shirt will be worn by participants to limit undesired motion of the markers due to loose clothing. Subjects will complete: